Mower suspension system and method

ABSTRACT

The mower front independent suspension assembly in some embodiments of the present invention includes a first suspension arm connected to the front of the lawn mower frame and a second suspension arm connected to the side of the lawn mower frame. In some embodiments, the first suspension arm is connected to the front of the frame at or near the longitudinal center of the frame, while the second suspension arm is connected to the side of the frame a distance from the front of the frame. Also, in some embodiments the cutter deck of the lawn mower is connected to the front independent suspension assemblies for movement therewith.

REFERENCE TO RELATED APPLICATIONS

This is a continuation of co-pending U.S. patent application Ser. No. 11/062,901 filed on Feb. 22, 2005, which is a continuation of U.S. patent application Ser. No. 10/285,350 filed on Oct. 31, 2002 and issued as U.S. Pat. No. 6,857,254, which is a continuation-in-part of U.S. patent application Ser. No. 09/879, 800 filed on Jun. 12, 2001 and issued as U.S. Pat. No. 6,510,678, which is a continuation of U.S. patent application Ser. No. 09/384,534 filed on Jul. 22, 1999 and issued as U.S. Pat. No. 6,244,025, which in turn is a continuation-in-part of U.S. patent application Ser. No. 09/359,537 filed on Jul. 22, 1999 and issued as U.S. Pat. No. 6,460,318, which in turn is a continuation-in-part patent application of (i) U.S. patent application Ser. No. 09/144,499, filed Aug. 31, 1998 and issued as U.S. Pat. No. 5,946,893, which in turn claims benefit from U.S. Provisional Patent Application Ser. No. 60/063,362 filed on Oct. 28, 1997; (ii) U.S. patent application Ser. No. 09/119,818 filed on Jul. 21, 1998 and issued as U.S. Pat. No. 6,170,242, which in turn claims benefit from U.S. Provisional patent Application Ser. No. 60/053,403 filed on Jul. 22, 1997 and U.S. Provisional Patent Application Ser. No. 60/063,362, filed on Oct. 28, 1997; and (iii) U.S. Patent application Ser. No. 08/898,801, filed on Jul. 23, 1997 and issued as U.S. Patent Number 6,062,333, which in turn claims benefit from U.S. Provisional Patent Application Ser. No. 60/022,865 filed on Jul. 26, 1996, all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention is described with respect to its use on lawn mowers, particularly self-propelled machines fitted with rotating blades for cutting grass and other vegetation. Numerous mowers exist in the marketplace for grass and vegetation. However, many of these mowers can produce uneven cuts and deliver unwanted stresses from the terrain to the driver and mower, resulting in driver fatigue and discomfort, mower wear and tear, more frequent repairs, and a shorter mower life.

In many typical mowers, the cutter deck is suspended as either a ground-following deck or a floating deck. A ground-following deck typically rides on caster wheels (e.g., a set of two or four caster wheels in many cases) and follows the contours of the ground. A floating deck is often suspended beneath the chassis between the front and rear wheels, such as by chains, sets of links and other elements. Other floating decks are suspended in various manners over the ground at a location in front of, behind, or beside the lawn mower frame. The floating deck is raised when skids, wheels, rollers, or other elements attached to the deck contact the lawn surface.

The height of a floating cutter deck from the surface being cut is often defined at least in part by the elevation of the mower's chassis. Generally, the intent for such a deck suspension system is to avoid continuing contact with the earth surface. When a cutter deck travels over uneven terrain having a strong grade, the cutter deck can contact the earth surface, and can cause the lawnmower blade(s) therein to scalp the surface being cut.

Cutter decks are generally designed to avoid scalping by rising or floating upwardly. This generally works for certain kinds of earth unevenness, but some scalping still occurs on severe terrain. Even if scalping can be avoided, cutter deck height relative to the earth surface can vary widely. This is also undesirable because it results in an unequal height of the cut grass.

A significant number of lawnmowers have wheels that are rigidly attached to the mower chassis. Unfortunately, when a mower having such a suspension encounters uneven terrain, the mower chassis can respond with significant upward and downward movement.

With regard to lawnmower front wheels, many conventional lawn mower designs either rigidly connect the front wheels to the chassis as just mentioned or employ a single axle to which the front wheels are attached. In some cases, the single axle can pivot about a point between the wheels, thereby generating slightly improved performance. Whether rigidly secured to the chassis or connected to a common axle, such front suspension designs either do not eliminate the undesirable upward and downward chassis movement described above, or only do so to a very limited extent. For example, if one wheel of such a mower rises in response to a rise in terrain, the single axle would cease to be parallel with the earth surface, generating forces that bring the chassis and cutter deck also out of a parallel relationship with the earth surface. The resulting cut of the grass is uneven and unsatisfactory.

In these and other conventional mowers, improved spring suspension systems are employed to reduce the amount of vertical chassis motion when one or more wheels encounter unevenness in the earth surface being traversed. These spring systems improve traction of such mowers by maintaining improved contact between the wheels and the surface being traversed. However, these spring suspension systems can cause or allow the chassis to roll relative to the cutting surface, such as, for example, when a mower is turned sharply or navigates a steep hillside. When a chassis rolls, a floating cutter deck (and in many cases, even a ground-following cutter deck) rolls with the chassis, resulting in one side of the cutter deck being closer to the cutting surface than the other. Consequentially, the cut of the grass is uneven and unsatisfactory.

In order to address cutting quality, rider comfort, and suspension wear problems, many conventional lawn mowers employ suspensions having one or more springs. Although such spring suspensions do represent an improvement and can help to address these problems, significant room for improvement still exists. For example, heavy riders or heavy mower accessories (e.g., grass catchers) tend to exert extra stress on the suspension springs, potentially causing the suspension springs to “bottom out” or to provide a limited range of spring motion. In either case, an uncomfortable ride results because the spring has limited or no capacity to absorb shock. As a result, an increased amount of shock is transferred to the mower and operator. The increase in shock can significantly shorten the life of the mower and can be a cause of more frequent mower maintenance and repair. Substituting a stiffer spring for heavy loading situations is an unattractive solution for many reasons, such as an uncomfortable ride in a light loading situation and additional low-level vibrations transmitted to the chassis.

In light of the shortcomings and problems of prior art lawn mowers described above, a need exists for a lawn mower having a suspension system that improves floating cutter deck and/or ground-following cutter deck motion, results in better cutting performance and quality, is relatively simple and inexpensive in construction, can limit undesirable chassis movement (such as chassis roll and large vertical chassis movement), provides a more comfortable ride, and can help prevent mower damage from vibration and shock. Each embodiment of the present invention provides one or more of these results.

SUMMARY OF THE INVENTION

Some embodiments of the present invention address one or more of the problems and limitations of the prior art by a unique connection assembly of the front wheels to the lawn mower frame. In some embodiments, the connection assembly for each front wheel includes a first suspension arm connected to the front of the frame and a second suspension arm connected to the side of the frame. The first suspension arm can be connected to the front of the frame at or near the longitudinal center of the frame, while the second suspension arm can be connected to the side of the frame a distance from the front of the frame. Either or both suspension arms can be mounted to the frame via plates secured to the frame. In some embodiments, the suspension arms are pivotably connected to the frame. Either or both suspension arms can be connected directly to a wheel yoke, can be connected to a support plate extending between the suspension arms, or can be connected to the wheel yoke and to a support plate extending between the suspension arms.

In some embodiments, front suspension assemblies are employed that have one or more springs positioned to bias the associated front wheel in a downward direction. The spring(s) can be located between the frame and the support plates (where used), can be located between either or both of the arms and the frame, or in still other manners to generate the same desired force. If desired, each suspension assembly can be provided with a spring, air bag, pneumatic or hydraulic cylinder, or other such device that compensates for heavy loads upon the suspension assemblies (i.e., “load compensation adjusters”). In some embodiments, the load compensation adjusters are adjustable to change the resistance to downward force provided by the associated suspension assemblies.

As described above, many conventional lawn mowers suffer from scalping and uneven cutting problems when the lawn mowers traverse uneven surfaces. Some embodiments of the present invention substantially reduce scalping and uneven cutting by suspending each of the front wheels independently from the front frame of the lawn mower with the structure described above. Upon wheel contact with uneven ground such as a steep upward or downward grade, the front wheels are therefore able to move generally vertically without greatly altering the relationship of the frame with respect to the surface traversed, or at least with reduced movement of the frame. In this manner, roll and pitch of the frame can be significantly reduced, resulting in a higher-quality cut and an improved ride.

By employing a two-arm spring suspension assembly connected as described above, the inventors have discovered that far less damaging vibration, shock, and impact received by the front wheels are transmitted to the frame and to the operator. By reducing the transmission of such vibration, shock, and impact shock to the chassis, the life of the lawn mower is considerably extended and the need for maintenance and repair is decreased.

In some embodiments of the present invention, the cutter deck is connected to the front and/or rear suspensions, and therefore move with vertical movement of the front and/or rear suspensions. In this manner, the cutter deck can follow the terrain traversed by the mower by following the vertical movement of the mower wheels.

In these and other embodiments, the front and/or rear suspension systems can be independent, and can be connected to a beam, subframe, or other structure that is pivotably coupled to the mower frame, thereby transmitting upward and downward force to the independent suspensions as well as to the pivoting beam, subframe, or other structure. Regardless of whether the cutter deck is also connected to these independent suspensions, this arrangement can result in improved suspension and cutter deck movement.

In addition, due to decreased vibration, shock, and impact transmitted by various embodiments of the present invention, a lawn mower provided with a suspension according to some embodiments the present invention can be operated at quicker speeds, resulting in increased lawn mower efficiency and decreased time needed to cut a surface. Also, the relatively simple design of some wheel suspensions according the present invention enables the suspension to be included in lawn mowers with little impact upon manufacturing and sales costs.

Other features and advantages of the present invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described with reference to the accompanying drawings, which show various embodiments of the present invention. However, it should be noted that the invention as disclosed in the accompanying drawings is illustrated by way of example only. The various elements and combinations of elements described below and illustrated in the drawings can be arranged and organized differently to result in embodiments which are still within the spirit and scope of the present invention.

In the drawings, wherein like reference numerals indicate like parts:

FIG. 1 is a perspective view of a lawn mower having a front suspension system according to an embodiment of the present invention;

FIG. 2 is a side elevation view of the lawn mower of FIG. 1;

FIG. 3 is a sectional perspective view of the front suspension system of the lawn mower illustrated in FIGS. 1 and 2;

FIG. 4 is a sectional perspective view of the front suspension system of the lawn mower illustrated in FIGS. 1-3;

FIG. 5 is a front elevation view of the lawn mower of FIG. 1;

FIG. 6 is a partial perspective view of a rear suspension system according to an embodiment of the present invention;

FIG. 7 is a partial perspective view of a portion of the rear suspension system of FIG. 6;

FIG. 8 is a partial side elevation view of a portion of the rear suspension system illustrated in FIGS. 6 and 7;

FIG. 9 is a partial rear elevation view of a portion of the rear suspension system illustrated in FIG. 6;

FIG. 10 is a partial rear elevation view of a portion of a rear suspension system according to another embodiment of the present invention;

FIG. 11 is a partial sectional view of a pre-compressed spring used the rear suspension system according to yet another embodiment of the present invention;

FIG. 12 is a cutaway view of a load compensation adjuster according to an embodiment of the invention, shown installed in the rear suspension system of FIGS. 6-9;

FIG. 13 is an elevation view of the load compensation adjuster of FIG. 12;

FIG. 14 is an elevation view of a shock absorber embodiment of the load compensation adjuster of the present invention;

FIG. 15 is an elevation view of an air shock embodiment of the load compensation adjuster of the present invention;

FIG. 16 is an elevation view of an airbag embodiment of the load compensation adjuster of the present invention;

FIG. 17 is an elevation view of an airbag embodiment of the load compensation adjuster of the present invention;

FIG. 18 is a partial view of a front or rear suspension system according to an embodiment of the present invention;

FIG. 19 is a partial view of a front or rear suspension system according to another embodiment of the present invention;

FIG. 20 is a perspective view of a mower having a front suspension system according to yet another embodiment of the present invention;

FIG. 21 is a perspective view of a mower having a front suspension system according to another embodiment present invention;

FIG. 22 is an exploded perspective view of the mower frame and front wheel independent suspension assemblies shown in FIG. 21;

FIG. 23 is an assembled perspective view of the mower frame and front wheel independent suspension assemblies shown in FIGS. 21 and 22;

FIG. 24 is an exploded perspective view of the mower deck lift assembly shown in FIG. 21;

FIG. 25 is a top plan view of the mower frame and front wheel independent suspension assemblies shown in FIGS. 21-24;

FIG. 26 is a front view of the mower frame and front wheel independent suspension assemblies shown in FIGS. 21-24;

FIG. 27 is a perspective view of a mower having a front suspension system according to another embodiment of the present invention;

FIG. 28 is an exploded perspective view of the mower frame and front wheel independent suspension assemblies shown in FIG. 27;

FIG. 29 is an assembled perspective view of the mower frame and front wheel independent suspension assemblies shown in FIGS. 27 and 28;

FIG. 30 is an exploded perspective view of the mower deck lift assembly shown in FIG. 27;

FIG. 31 is a perspective view of a mower having a front suspension system according to another embodiment of the present invention;

FIG. 32 is an exploded perspective view of the mower frame and front wheel independent suspension assemblies shown in FIG. 30;

FIG. 33 is an assembled perspective view of the mower frame and front wheel independent suspension assemblies shown in FIGS. 31 and 32; and

FIG. 34 is an exploded perspective view of the mower deck lift assembly shown in FIG. 31.

DETAILED DESCRIPTION

Referring to FIGS. 1-2, a lawn mower 10 includes a seat 12 connected to a chassis 14. Chassis 14 in turn rests on a main frame 16. Two rear wheels 18 are connected to main frame 16 by the independent suspension (not shown) as described in co-pending U.S. patent application Ser. No. 09/119,818. Two front wheels 22 are connected to main frame 16 via a front suspension system, shown generally at 24. A floating cutter deck 20 is preferably suspended beneath main frame 16 by rear suspension chains 26 and front suspension chains 28. Each rear suspension chain 26 is preferably connected to a rear wheel bracket 30 which is “wheel-side” of the rear independent suspension system. Each front suspension chain is preferably connected to a deck height adjustment mount 32 which is part of front suspension section 24. Suspending cutter deck 20 from the “wheel-side” of the front and rear independent suspensions ensures that cutter deck 20 moves vertically up and down in response to the vertical motion of front wheels 22 and rear wheels 18, which in turn are responsive to the terrain being mowed. Scalping and uneven cuts of the grass are thus prevented.

Although the mower of the present invention can be equipped with either a ground-following cutter deck or a floating cutter deck, using a floating cutter deck with a mower having independent suspension requires additional considerations. Rolling of a lawn mower chassis is induced under certain situations. Among them are: (a) when the mower changes direction while traveling forward and centrifugal force acts laterally at the center of gravity of the machine; (b) when the mower traverses a slope and the gravitational force vector shifts direction relative to the plane of the mower wheel tread, and (c) when the mower travels over a surface undulation, lifting or lowering one or both wheels on one side, thereby rotating the mower chassis in space.

Conventional mowers typically use wheels that are rigidly connected to the chassis. In these mowers, the chassis cannot roll relative to the wheels; therefore, there is no rolling of types (a) and (b). Other conventional mowers have a pivoting front or rear axle at one end, with an opposing end axle rigidly attached to the chassis. In these mowers, the rigidly attached axle limits the chassis roll which the pivoting axle otherwise permits to the extent the chassis is sufficiently rigid. The mower of the present invention, preferably having both front and rear independent wheel suspension systems, beneficially minimizes any rolling of the machine when a wheel passes over certain small bumps and depressions—type (c) rolling. Nonetheless, larger bumps and depressions can induce rolling.

As will be explained below, the suspension configuration of FIG. 9 is prone to rolling of types (a) and (b). if cutter deck 20 of mower 10 is suspended from the chassis, rolling may adversely affect the essential mower function, that is, cutting grass to an even height. In particular, when the chassis rolls and one side moves closer to the earth surface, a cutter deck suspended from the chassis also moves closer to the surface. Therefore, the preferable embodiment of the present invention couples the motion of the cutter deck to the motion of a sprung wheel rather than directly to the chassis, thereby reducing the change in cutter deck height relative to the mowed surface when the chassis rolls.

Due to the large cutting width preferred in commercial mowers and the distance between the front wheels 22, rocks or other uneven terrain features that are avoided by front wheels 22 can damage cutter deck 20. Cutter deck 20 therefore preferably includes a front roller 34, a rear roller 36 (partially hidden by rear wheel 18 in FIG. 2), and front caster wheels 38 that protect cutter deck 20 from damage.

Referring to FIGS. 3-5, front suspension system 24 includes a longitudinal suspension strut 40 that is connected to main frame 16 via an upper suspension strut 42 and a lower suspension strut 44. Front wheel 22 is connected to longitudinal strut 40 via a trunnion 39. Upper and lower suspension struts 42, 44 pivotably connect to main frame 16 at a plurality of main frame pivot points 46 and pivotably connect to longitudinal suspension strut 40 at a plurality of front suspension pivot points 48. A spring 50 is fixed between a spring bracket 52 of upper suspension strut 42 and a front transverse member 54 of main frame 16 so that upward movement of suspension system 24 compresses spring 50 between spring bracket 52 and front transverse member 54. Upper and lower suspension struts 42, 44 are preferably of equal length so that the suspension travel does not change the perpendicularity of front wheel 22 to the ground.

As front wheels 22 move vertically up and down in response to the terrain, the front of cutter deck 20, being connected to longitudinal suspension strut 40 via adjustment mount 32, moves vertically up and down in response to the vertical motion of front wheels 22. Main frame 16 is isolated from the vertical motion of front wheels 22 by front suspension system 24.

Referring to FIGS. 6-9, a rear suspension system for mower 10 includes a motor mount 86 connected to main frame 16 via upper links 62 and lower links 64. Two struts 78 join an upper frame member 74 of main frame 16 to a lower frame member 76 of main frame 16. Upper and lower links 62, 64 are connected to struts 78 at main frame pivot points 66 and to motor mount 86 at rear suspension pivot points 68. Upper and lower links 62, 64 are shown in this embodiment as being of equal length. A spring 72 is captured between a spring bracket 70 of upper frame member 74 and a motor 80. FIG. 8 additionally shows an optional disk 84 on a wheel hub 82 that is used with disk brakes instead of the more conventional band-drum brakes typically used on prior art lawn mowers.

Referring specifically to FIG. 9, a roll center is an imaginary point about which a mower with movable suspension elements tends to roll when subjected to lateral forces. A roll axis of the mower runs through the front and rear roll centers. The location of a roll center R for the rear wheel suspension system is determined by examining the intersection of an upper link phantom line 90 and a lower link phantom line 89. Line 90 runs through the pivot points for upper link 62 while line 89 runs through the pivot points for lower link 64. A ground contact phantom line 88 runs from a ground contact point 92, representing the contact between rear wheel 18 and ground 94, to the intersection of lines 90 and 89. In the embodiment described above, where upper and lower links 62, 64 are of equal length, lines 90 and 89 intersect at infinity. Line 88 therefore intersects lines 90 and 89 at infinity; line 88 is thus parallel to lines 90 and 89. The intersection of line 88 with a vertical plane passing through a center of gravity (mass) of the mower is the location of roll center R.

In this embodiment, roll center R is substantially lower in elevation than the center of gravity CG of the mower. The location of roll center R can be moved vertically by changing the lengths and angles of the link assemblies. With roll center R significantly below center of gravity CG, the mower tends to sway or rock to the side when turning. Sway bars (not shown), also known as anti-sway or anti-roll bars, are optionally added to this equal-link-length suspension to inhibit swaying during turning. Such bars are typically torsion bars or other elastic structure which, when one wheel moves closer to the chassis, resist such motion with a force, the reaction to which is applied to the opposite wheel. Notwithstanding the tendency to roll, the FIG. 9 suspension provides a better vehicle ride and absorption of bumps compared to an unequal link-length suspension. The FIG. 9 suspension also minimizes lateral motion when the mower load changes, such as when an operator mounts or dismounts the mower, removes a grass-catcher bag, or when there are changes in the mower's vertical momentum due to uneven terrain.

Referring to FIG. 10, an embodiment is shown with unequal link lengths. An upper link 62′ is shorter than a lower link 64′, with the lengths of links 62′, 64′ preferably determined such that the roll center R and the center of gravity CG substantially coincide. As shown in the figure, phantom lines 90′ and 89′ intersect at R, so ground contact line 88′ intersects the vertical plane passing through the center of gravity CG at the center of gravity CG. This configuration minimizes the roll tendency of the mower during turning.

Referring to FIG. 11, a way of pre-compressing spring 72 is shown. Pre-compression is desirable to lessen the movement of the mower chassis when the mower operator mounts and dismounts the mower. Pre-compression is preferably accomplished by pivotably attaching a threaded guide rod 96 to motor 80. Rod 96 extends through a hole 97 in spring bracket 70 with a nut 98 on the threaded end of rod 96. Nut 98 is preferably adjustable so that the amount of pre-compression can be changed when required.

Referring to FIGS. 12-13, a load compensation adjuster such as overload spring 100 is installed inside spring 72. If suspension spring 72 is a closed, ground end, compression spring with a right hand helix, overload spring 100 is preferably a closed, ground end, compression spring with a left-hand helix. Overload spring 100 fits inside spring 72 and is approximately one inch shorter in length than spring 72. The shorter length of overload spring 100 allows spring 72 to operate at its existing rate, but when spring 72 is compressed more than one inch, overload spring 100 begins to help carry the extra weight. Overload spring 100 is preferably wound with coils in the opposite direction from spring 72. The characteristics of the preferred embodiment of overload spring 100 is detailed in Table 1. Spring type compression spring, closed and grounded end Material chrome silicon Wire Diameter 0.2340 in. Mean Diameter 1.0160 in. Inside diameter 0.7820 in. Outside Diameter 1.2500 in. Total Coils 15.6984 in. Pitch 0.3308 in. Pitch Angle 5.9177 deg. Weight 0.6120 lbs. Free Length 5.0000 in. Solid Height 3.6734 in. Load Rate (lbs./in.) 5.00 in. (free length) @ 0 lbs. @150 lbs. 4.50 in. @300 lbs. 4.00 in. @398 lbs. 3.67 in. (solid height)

Referring to FIG. 14, load compensation adjustment is achieved using an alternative embodiment such as a shock absorber 102 inside spring 72 in place of overload spring 100. This arrangement is commonly referred to as a coil-over suspension.

Referring to FIG. 15, load compensation adjustment is achieved using an alternative embodiment such as an air shock 104 instead of shock absorber 102, although not depicted inside spring 72 in the figure. Using air shock 104 allows adjustment of the spring tension by raising or lowering the air pressure, thereby determining the spring load or tension.

Referring to FIG. 16, load compensation adjustment is achieved by using an alternative embodiment such as an airbag 106 to replace overload spring 100 inside spring 72. Airbag 106 can be inflated or deflated for the desired suspension, either by the user of pre-inflated at the factory.

Referring to FIG. 17, an alternative embodiment for load compensation adjustment includes an airbag 108 which could replace the spring within a spring combination by acting as a variable compression spring. As the air in airbag 108 becomes compressed, the force required to compress it further increases.

Referring to FIG. 18, a torsion bar suspension is shown connected to wheel hub 82 at the left rear wheel location for mower 10. A first torsion bar 112 is hooked to lower link 64 at one end, while another end attaches to an adjuster 114, which permits adjustment of the tension of torsion bar 112. In similar fashion, a second torsion bar 110 is hooked to the lower link 64 on the right side of mower 10, with the other end of torsion bar 110 being attached to an adjuster 116 which is connected to lower link 64 on the left side of mower 10. The right side wheel hub and upper and lower links are not shown in FIG. 18. The torsion bars 110, 112 replace the springs 72 to provide the rear wheel suspension. Load compensation is done with adjusters 114, 116. Although the torsion suspension is shown for the rear wheels, it can be used on the front wheels as well. For the front suspension system shown in FIG. 4, front transverse member 54 and springs 50 are replaced by the torsion bars in the manner just described with respect to the rear suspension system.

Referring to FIG. 19, an alternative embodiment of the front suspension system includes a torsion bar 118 attached to lower suspension strut 44 near the lower main frame pivot point 46. Torsion bar 118 is approximately 1.5 to 2.5 feet (45 to 76 cm) long and extends lengthwise to attach to main frame 16. A similar arrangement provides the front suspension for the other front wheel.

Referring to FIG. 20, in another embodiment of the present invention, a main frame 122 is connected to a pivoting subframe 124 that incorporates a front suspension system. Pivoting subframe 124 includes a left half subframe 124 a which is hingeably connected to a right half subframe 124 b. Two hinges, such as a front clevis joint 135 and a rear clevis joint 137, connect left and right half subframes 124 a, 124 b to each other. A front pivot pin 146 acts as the clevis pin for front clevis joint 135 while a rear pivot pin 148 acts as the clevis pin for rear clevis joint 137. Front pivot pin 146 is connected to a front transverse member 147 of main frame 122 via a front pivot plate 142, while rear pivot pin 148 is connected to a rear transverse member 149 of main frame 122 via a rear pivot plate 144.

A left spring pocket 140 a, connected to an extension of main frame 122, houses a left spring 138 a that abuts a front transverse portion 151 a of left half subframe 124 a, while a right spring pocket 140 b, connected to an extension of main frame 122, houses a right spring 138 b that abuts a front transverse portion 151 b of right half subframe 124 b. Thus, when a left caster wheel 136 a rolls into a dip, left half subframe 124 a moves with it, not affecting right half subframe 124 b or main frame 122. Similarly, when a right caster wheel 136 b rolls into a dip, right half subframe 124 b moves with it, not affecting left half subframe 124 a or main frame 122. Thus, three of the four mower wheels are on the ground at any given time, resulting in a stable, smooth ride with little or no scalping caused by the cutter deck.

In the embodiment illustrated in FIG. 20, rear suspension chains 153 for a cutter deck 150 are attached to rear wheel brackets 155 via a cutter deck lift assembly 156, while front suspension chains 158 for cutter deck 150 are attached via cutter deck lift assembly 156 to main frame 122. The weight distribution in a lawn mower of this type is approximately 75% in the rear and 25% in the front. Thus, whereas the rear of the cutter deck is preferably connected to the rear wheel brackets instead of the main frame to avoid scalping during sharp turns or over rough terrain, the front of the cutter deck is preferably connected directly to the main frame in this embodiment.

FIGS. 21-26 illustrate another embodiment of the present invention. The lawn mower 200 illustrated in FIGS. 21-26 includes a motor 202, a motor cover 204, a chassis 212, a front frame 214, a pair of front wheels 222, a pair of rear wheels 206 (only one of which is visible in FIG. 21), a cutter deck 208, a seat 210, and a pair of front wheel independent suspension assemblies 216. The particular type of lawn mower 200 illustrated in FIG. 21 is presented by way of example only. In this regard, the suspension systems of the present invention can be employed on any type of riding or non-riding lawn mower.

In the type of lawn mower illustrated in FIG. 21, the motor 202 is mounted to the chassis 212 and is covered by the motor cover 204. Also, the chassis 212 is mounted to the front frame 214, which can be a separate frame connected to a rear frame (not shown) in any conventional manner or can define a front portion of a single frame of the lawn mower 200. In some embodiments, the lawn mower 200 simply has a single frame 214 upon which the motor 202 is mounted (whether by a chassis 212 or otherwise).

With reference to FIGS. 21 and 24, the rear wheels 206 of the lawn mower 200 can be mounted to the chassis 212 by a pair of rear wheel independent suspension assemblies 207, although the rear wheels 206 can instead be rigidly mounted to the mower front frame 214, can be connected to an axle that is pivotable with respect to the front frame 214, or can be attached to the front frame 214 in any other manner. Examples of rear wheel independent suspensions 207 are provided in U.S. Pat. No. 6,244,025, the disclosure of which is incorporated herein by reference insofar as it relates to rear wheel independent suspension systems.

The cutter deck 208 of the lawn mower 200 can be in any location with respect to the front and rear wheels 222, 206 and with respect to the front frame 214. However, in the embodiment illustrated in FIG. 21, the cutter deck 208 is positioned between the front and rear wheels 222, 206. The cutter deck 208 contains at least one cutter (not shown) for cutting grass or other vegetation on a surface, and in some embodiments can be raised and lowered with respect to the ground.

The cutter deck 208 can be a floating or ground-following cutter deck. The cutter deck 208 according to the present invention can be directly or indirectly connected to the frame of the lawn mower 200 in a number of different manners, some of which provide different types of cutter deck movement and cutter deck performance. For example, the cutter deck 208 can be suspended entirely from the frame of the lawn mower 200, can be suspended at the front and rear from front and rear independent suspension systems, can be suspended from the front by front independent suspension systems while being suspended from the rear by the frame of the lawn mower 200, or can be suspended from the rear by rear independent suspension systems while being suspended from the front by the frame of the lawn mower 200. Examples of the latter three types of cutter deck suspensions are provided in the embodiments of the present invention illustrated in FIGS. 27-30, 31-34, and 21-26, respectively.

The floating cutter deck 208 illustrated in FIG. 21 is presented by way of example only. In this embodiment, the cutter deck 208 is connected to and suspended from the front frame 214. Connection to the rear independent suspension assemblies 207 permits the cutter deck 208 to follow upward and downward movement of the rear wheels 206 in response to changing terrain elevation, thereby maintaining the cutter deck 208 in a more stable relationship with respect to the ground even as the lawn mower 200 traverses uneven terrain.

With continued reference to the embodiment of the present invention illustrated in FIGS. 21-26, the front end of the cutter deck 208 is not responsive to upward and downward movement of the front wheels 222. However, the rear end of the cutter deck 208 follows the upward and downward movement of the rear wheels 206 by virtue of the cutter deck's connection to the rear independent suspension assemblies 207. Such connection can be established in a number of different manners, such as the bolts 213 coupled at one end to respective brackets 219 on the rear end of the cutter deck 208 and to respective crank arms 221 pivotably coupled to the rear independent suspension assemblies 207. In other embodiments, the cutter deck 208 can be coupled to the rear independent suspension assemblies 207 in any other manner desired, such as by securing chains, cables, links, straps, bars, or other elements to the cutter deck 208 and to the rear independent suspension assemblies 207. Further examples of manners in which the rear of the cutter deck 208 can be directly or indirectly connected to the rear independent suspension assemblies 207 are provided below with regard to front independent suspension assemblies in FIGS. 27-30.

In the embodiment of the present invention illustrated in FIGS. 27-30, the mower 400 suspends the cutter deck 408 at one end from one or more front independent suspension assemblies 416, and at another end from one or more rear independent suspension assemblies 407. The cutter deck 408 can be connected to the front suspension assemblies 416 for suspension therefrom in a number of different manners, such as by securing chains, cables, links, straps, bars, or other elements to the cutter deck 408 and to the suspension assemblies 416. Such elements can be connected to the suspension assemblies by bolts, screws, hooks, pins, or other fasteners, by inter-engaging elements, and in some cases by permanent connections such as welding, brazing, and the like. As will be described in greater detail below, the elements employed to suspend the cutter deck 408 from the suspension assemblies 416 can be connected directly to the suspension assemblies or can be connected thereto via a deck lifting device (such as that shown in FIGS. 27 and 30). In this regard, the elements employed to suspend the cutter deck 408 from the suspension assemblies 416 can be connected to one or movable or immobile levers, bars, or other elements connected to the suspension assemblies 416. The elements employed to suspend the cutter deck 408 from the suspension assemblies 416 can be connected to the cutter deck 408 in any manner desired, including the manners of connection described above with reference to connections to the suspension assemblies 416.

By way of example only, the cutter deck 408 illustrated in FIGS. 27 and 30 is suspended by chains, each of which are connected at one end to an eyebolt on the cutter deck 408 and at another end to a crank arm 451 pivotably connected to a corresponding suspension assembly 416 via a mounting block 450. The mounting blocks 450 can be integral with or welded to the second suspension arms 448, and in other embodiments can be connected in other suitable manners, such as by clamping, bolting, and the like. In still other embodiments, the crank arm 451 can be pivotably connected to the suspension arm 448 by a post of the crank arm 451 received within an aperture in the suspension arm 448 (or vice versa). It will be appreciated by one having ordinary skill in the art that the chains employed to suspend the cutter deck 408 in such embodiments can be coupled directly or indirectly to the suspension arm 448 (or any other location on the independent suspension assembly 416) in a number of other manners, each of which fall within the spirit and scope of the present invention.

As mentioned above, the rear of the cutter deck 408 in the embodiment illustrated in FIGS. 27-30 is suspended from the rear independent suspension assemblies 407. The rear of the cutter deck 408 can be connected to the rear independent suspension assemblies in any of the manners described above with reference to the same connection in the embodiment illustrated in FIGS. 21-26, and the connections described above between the front of the cutter deck 408 and the front independent suspension assemblies 416. By way of example only, and with particular reference to FIG. 30, the rear of the cutter deck 408 can be suspended by chains 410 connected to bolts 453 on the cutter deck 408 and to rear crank arms 452 pivotably connected to the rear independent suspension assemblies 407.

By virtue of the suspended connections of the cutter deck 408 from the front suspension assemblies 416, 417 (and if desired, from the rear independent suspension assemblies 407), the cutter deck 408 can follow upward and downward movement of the wheels 422, 406 in response to changing terrain elevation, thereby maintaining the cutter deck 408 in a more stable relationship with respect to the ground even as the lawn mower 400 traverses uneven terrain.

In yet another embodiment of the present invention illustrated in FIGS. 31-34, the cutter deck 508 is suspended at one end from front independent suspension assemblies 516, and at another end from the frame 514. The front of the cutter deck 508 can be suspended from the front independent suspension assemblies 516 in any of the manners described above with regard to cutter deck suspension in the earlier embodiments. By way of example only, the front end of the cutter deck 508 is coupled to suspension arms 548 of the front independent suspension assemblies 516 via front crank arms 551 pivotably coupled to the front independent suspension assemblies (such as by front mounting blocks 550 welded to the suspension arms 548 or otherwise connected thereto in any suitable manner, such as by clamping, brazing, or integrally-forming the front mounting blocks 550 with the suspension arms 548). As a result, the front end of the cutter deck 508 is responsive and follows upward and downward movement of the front wheels 522.

With continued reference to the embodiment of the present invention illustrated in FIGS. 31-34, the rear end of the cutter deck 508 can be suspended from the frame 514 in any of the manners described above with regard to cutter deck suspension in earlier embodiments. By way of example only, the rear end of the cutter deck 508 is coupled to the frame 514 via rear crank arms 552 pivotably coupled to the frame 514 (such as by rear mounting blocks 553). As a result, the rear end of the cutter deck 508 is not responsive to upward and downward movement of the rear wheels 506.

In the embodiments illustrated in FIGS. 21-34, the cutter deck 208, 408, 508 is attached to the front and/or rear independent suspension systems in any manner desired, such as by chains or cables, by links, hinges or joints, by conventional fasteners such as bolts, screws, rivets, hooks, clips, and the like. For example, in the embodiment illustrated in FIGS. 21-26, the cutter deck 208 is coupled to the front frame 214 and rear independent suspension assemblies 207 via deck hanger assemblies 209 that include conventional threaded fasteners 223 passed through brackets 225 on the cutter deck 208. As another example, in the embodiment illustrated in FIGS. 27-30, the deck hanger assemblies 409 include conventional fasteners such as, for example, eyebolts, that are used in conjunction with chains to couple the cutter deck 408 to the front and the rear suspension assemblies 416, 407. In the exemplary embodiment illustrated in FIGS. 30-34, the deck hanger assemblies 509 include conventional fasteners such as, for example, U-bolts, that used in conjunction with chains to couple the cutter deck 508 with the front suspension assemblies 516 and the frame 514.

The deck hanger assemblies 209, 409, 509 can be attached directly to the front and/or rear independent suspension assemblies (such as to arms, flanges, or other portions of the front and/or rear independent suspension assemblies, within apertures in the front and/or rear independent suspension assemblies, and the like), or can be indirectly connected thereto by cutter deck lifting assemblies 211, 411, 511. For example, the deck hanger assemblies 209, 409, 509 in the illustrated embodiments of FIGS. 21-34 are connected to bell cranks, arms, or other elements movable by a user to lift and lower the cutter deck 208, 408, 508 with respect to the ground. Such bell cranks, arms, and other elements can be lifted and lowered by levers, pedals, cranks, motors, hydraulic or pneumatic actuators, or by any other manual or powered device. Still other devices and elements for raising and lowering a cutter deck 208, 408, 508 are well known to those skilled in the art and are not therefore described further herein.

With reference again to the embodiment of the present invention illustrated in FIGS. 22-26, the mower 200 can have a chassis 212, a front frame 214 (or front portion of a main frame 214), and a pair of front wheel independent suspension assemblies 216. The front frame 214 can be connected to the chassis 212 by a plurality of bolts or other threaded fasteners 218. Other manners of fastening the front frame 214 to the chassis 212 can instead be used. By way of example only, the front frame 214 can be connected to the chassis 212 by screws, rivets, pins, welding or brazing, inter-engaging elements, and the like, and can even be integral with the chassis 212 in some embodiments. For purposes of reference in the following description, a substantially horizontal axis 220 runs through the center of the front frame 214 and chassis 212 to divide the front frame 214 and chassis 212 into two sides. In some embodiments, the front frame 214 has opposite sides and has a front, each of which are defined by one or more beams, rods, bars, plates, or other structural members. For example, the front frame 214 in the illustrated embodiment is defined by tubular side beams 215 and a tubular front beam 217 connected together by welds (although any other manner of connecting these elements together can instead be employed, including those mentioned above with regard to connection of the chassis 212 and frame 214). The side beams 215 in the exemplary embodiment of FIGS. 21-26 are substantially parallel to the horizontal axis 220, while the front beam 217 is substantially orthogonal to the horizontal axis 220. However, any other relative orientations of these beams 215, 217 can instead be employed.

As will be appreciated by one having ordinary skill in the art, the frame 214 of the present invention can be constructed of a wide variety of structural elements. In some embodiments, these elements include tubular beams as mentioned above. Tubular beams provide a relatively strong and lightweight framework for the lawn mower 200 compared to other structural members that can be employed. In other embodiments however, the front frame 214 can be constructed partially or entirely of different structural members, including without limitation bars, rods, non-tubular beams having any cross-sectional shape (e.g., L-shapes, I-shapes, C-shapes, etc.), plates, and the like. Accordingly, as used herein and in the appended claims, the term “beam” (whether referring to the front beam 217, a side beam 215, or any other beam of the front frame 214) is intended to encompass all of these structural members.

With continued reference to FIG. 22, the illustrated lawn mower 200 has a pair of front wheel independent suspension assemblies 216 connected to the front frame 214. Although the independent suspension assemblies 216 can be different in structure, elements, and/or connection, both independent suspension assemblies 216 in the illustrated embodiment contain identical components and are mirror images of each other with respect to the horizontal axis 220. Each of the independent suspension assemblies 216 has a ground-contacting wheel 222. However, the independent suspension assemblies 216 can instead have other types of rolling devices, including without limitation rollers, balls, and tires connected in any conventional manner for rotation and for support of the front frame 214. For example, each of the caster wheels 222 can be supported by an axle 224 attached to an inverted yoke 226. Other types of rolling element mounting methods are possible, such as a bent axle extending outward and upward from the axis of rotation of the rolling element for connection to the rest of the independent suspension assembly 216.

In some embodiments, each front wheel 222 is capable of pivoting about a vertical or substantially vertical axis. In this regard, the front wheels 222 can be pivotably connected to the rest of the front independent suspension assemblies 216 in a number of different manners. For example, the yokes 226 of the caster wheels 222 in the illustrated embodiment are pivotably connected to the rest of the front independent suspension assemblies 216 by posts 228 extending vertically or substantially vertically from each yoke 226. These yokes 226 are pivotably connected to the rest of their respective suspension assemblies 216 in any conventional manner. By way of example only, a washer 230, 237 and bearings 232, 235 are received on the posts 228 in the illustrated embodiment, and enable the posts 228 and yokes 226 to pivot with respect to the front frame 214.

Each front independent suspension assembly 216 illustrated in the embodiment of FIGS. 21-26 has a first suspension arm 246 connecting the associated front wheel 222 to a front of the frame 214 and a second suspension arm 248 connecting the associated front wheel 222 to a side of the front frame 214. The posts 228 in the illustrated embodiment are pivotably connected to the suspension arms 246, 248 by being received within and connected to a joint 236 connected to the suspension arms 246, 248. Each joint 236 can take a number of different forms, and in the embodiment of FIGS. 21-26 is a cylindrical member within which the post 228 is received. Each post 228 is preferably secured within a corresponding joint 236 by a nut 238 or other threaded fastener screwed upon a threaded end of the post 228 as best shown in FIG. 22. If desired, additional hardware can help secure this connection. For example, one or more cotter pins 240 can be clipped to the nut 238 and/or post 228, can be received within an aperture or recess within the nut 238 and/or post 228, or can be connected to the post 228 in any other conventional manner to prevent disconnection of the nut 238 from the post 228. As another example, one or more washers 237 can be provided as needed to distribute force and secure the connection of the posts 228 to the joints 236.

As an alternative to the use of a cylindrical joint 236 as described above in order to connect the post 228 of each front independent suspension assembly 216 to the suspension arms 246, 248, the joint 236 can be a socket within which an end of the post 228 is received, can be defined by an aperture in either or both suspension arms 246, 248, and the like. Any conventional joint structure can be employed to establish this connection of the post 228 and wheel 222, each of which falls within the spirit and scope of the present invention.

An advantage of a cylindrical joint 236 as described above is the ability to receive bearings 232, 235 therein and to house and protect the bearings 232, 235. In this regard, other elements and structure can be used to enable the wheels 222 to pivot properly. For example, depending upon the type of joint 236 employed, ball bearings, roller bearings, sleeves or linings made of low-friction material, and other elements can be used as desired (with or without lubricating material). In the illustrated embodiment, two sets of roller bearings 232, 235 are received within the joint 236, and can be seated within lips, ledges, or other structure of the joint 236. However, any other manner of retaining these and other types of bearings can be used, depending at least partially upon the type of joint 236 employed to connect the wheels 222 with respect to the rest of the front independent suspension assemblies 216.

Although a threaded connection is employed in some embodiments to secure the post 228 with respect to the rest of the front independent suspension assembly 216, it should be noted that a number of other type of connections can be used. By way of example only, the post 228 can be snap-fit, press-fit, or screwed into the joint 236 (or within a collar, lug, socket, or other fitting within the joint 36), can be assembled on opposite ends or sides of the joint 236 using any conventional fasteners, and the like.

In some embodiments, it may be desirable to protect the joint 236 and its components from dirt, debris, and other foreign materials and to retain any lubricant material therein. To this end, the joint 236 can be capped, can be received within a boot, grommet, housing, or shroud, and the like. For example the joint in the embodiment shown in FIGS. 21-26 is covered with a cap 242.

As mentioned above, each front independent suspension assembly 216 in the embodiment of FIGS. 21-26 has a first suspension arm 246 connecting a front wheel 222 to a front of the frame 214 and a second suspension arm 248 connecting the front wheel 222 to a side of the front frame 214. The first suspension arms 246 can be connected at a common location on the front of the frame 214 (whether by a common bolt 264 or other fastener, by another common connection, or otherwise). Alternatively, the first suspension arms 246 can be connected to the front of the frame 214 at different locations along the front of the frame 214.

In some embodiments, the first and second suspension arms 246, 248 are elongated tubular elements connected to form an acute angle therebetween. However, the first and second suspension arms 246, 248 can instead be bars, beams, or other elongated elements that connected to define an angle therebetween (and in some embodiments, an acute angle therebetween). The suspension arms 246, 248 can have any relative length. In the illustrated embodiment for example, the first suspension arm 246 is shorter than the second suspension arm 248. The suspension arms 246, 248 in the embodiment of FIGS. 21-26 are welded to the joint 236. In other embodiments, the suspension arms 246, 248 can be connected to the joint 236 in any other manner, including without limitation by brazing, by one or more conventional fasteners such as screws, bolts, rivets, clamps, clips, and the like, by pin and aperture, finger and slot, hook and aperture, and other types of connections, by threaded, press-fit, or snap-fit connections, by inter-engaging elements, and the like.

As an alternative to direct connection to the joint 236, either or both suspension arms 246, 248 can be indirectly connected to the joint 236, such as by connection to a brace, strut, plate, reinforcement or other element connected to the joint 236, by connection of the first suspension arm 246 directly to the joint 236 and by connection of the second suspension arm 248 to the first suspension arm 246 (or vice versa), and the like.

The use of two suspension arms 246, 248 of each front independent suspension enables connection of each front independent suspension assembly 216 to two different locations on the front frame 214: (i) one location at the front of the frame 214 and one location at the side of the front frame 214, (ii) two locations at the front of the frame 214, or (iii) two locations at the side of the front frame 214. Although two suspension arms 246, 248 are preferred for this purpose, one having ordinary skill in the art will appreciate that the same results can be achieved by using other elements and structures.

For example, the suspension arms 246, 248 can be replaced by a single arm having a shape similar to the shape formed by two separate suspension arms 246, 248. Also, the suspension arms 246, 248 can be supplemented by additional suspension arms to form a double wishbone suspension system, including upper first and second suspension arms and lower first and second suspension arms. As an alternative to the manner of connection illustrated in FIGS. 21-23, 25, and 26, such upper and lower first suspension arms may be connected to the front of the frame 214 or the side of the front frame 214 along with the upper and lower second suspension arms. Additionally, the upper and lower first and second suspension arms can all be connected to the front of the frame 214. As yet another example, a plate can be shaped to connect to the front of the frame 214 and to extend around a front corner of the frame 214 for connection to a side of the front frame 214. Still other elements and structure can be employed to connect the joint 236 to the front and side of the front frame 214, or to connect the joint 236 to only the front or only the side of the front frame 214, each of which falls within the spirit and scope of the present invention.

Each of the suspension arms 246, 248 can be connected directly to the front frame 214 in a number of different manners. In some embodiments, the suspension arms 246, 248 are pivotably connected to the front frame 214 to enable upward and downward movement of the front independent suspension assemblies 216. Any type of pivotable connection can be employed, such a ball and socket connection, a pivot and aperture connection, a hinge connection, and the like. One having ordinary skill in the art will appreciate that still other manners of pivotal connection are possible. In the illustrated embodiment of FIGS. 21-26, both suspension arms 246, 248 are pivotably connected to the front frame 214 by bolts 264 as will be described in greater detail below.

Although direct connection to the front frame 214 is possible, the suspension arms 246, 248 in some embodiments are connected to plates, bars, rods, or other elements shaped to provide an improved interface between the suspension arms 246, 248 and the front frame 214. More specifically, the suspension arms 246, 248 in many embodiments are oriented at an angle with respect to that part of the front frame 214 to which they connect, thereby making such a connection more difficult. Therefore, the suspension arms 246, 248 of some embodiments are connected to elements shaped to better establish an angled connection to the front frame 214. In the illustrated embodiment of FIGS. 21-26 for example, the first suspension arm 246 is connected to a suspension front plate 250 on the front of the front frame 214, while the second suspension arm 248 is connected to a suspension side plate 251 of the side of the front frame 214. The suspension front and side plates 250, 251 in this exemplary embodiment are welded to the front frame 214, but can be connected thereto by fasteners or in any of the manners described above with reference to the connection between the first and second suspension arms 246, 248 and the joint 236. In some embodiments, the suspension front and side plates 250, 251 can even be integral with the front frame 214, such as by being stamped, molded, pressed, cast, or otherwise defined by a part of the front frame 214.

Each first suspension arm 246 can be pivotably connected to the front of the frame 214 (and in some cases, to a common suspension front plate 250 as shown in FIGS. 21-26 or to respective suspension front plates) by a front pivot assembly 252. As mentioned above, the front pivot assembly 252 can take a number of different forms. In the illustrated embodiment for example, the front pivot assembly 252 includes a ball joint 260 attached the first suspension arm 246 by a threaded fastener such as a nut 258 threaded onto a threaded extension of the ball joint 260, a pair of joint seals 262, and a bolt 264 passed through apertures in the ball joint 260 and joint seals 262. If desired, a spacer 266 can be located between the ball joint 260 and the front plate 250 to provide clearance between the ball joint 260 and the front plate 250. The ball joint 260 can instead be connected to the first suspension arm 246 by being threaded into a threaded aperture therein, by one or more conventional fasteners, or in any of the manners described above with reference to the connection between the first and second suspension arms 246, 248 and the joint 236. Although not required, the joint seals 262 can be employed for purposes of keeping the ball joint 260 free of dirt, debris, and foreign matter.

A bolt 264 can be employed for pivotable connection to the ball joint 260 as described above. However, the bolt 264 can be replaced by any other element received within the ball joint 260, including without limitation a pin or rod, a headed post, extension, or any other element extending into the ball joint 260 from the front plate 250 or frame 214. In other embodiments, a ball joint socket 260 be attached to the front plate 250 or frame 214 and can pivotably receive a pin, rod, headed post, extension, or other element attached to the first suspension arm 246. The bolt 264 of the front pivot assembly 252 can extend into an aperture in the suspension front plate 250 and can be secured therein by a nut 268 or other conventional fastener.

As discussed above, the suspension front plate 250 can be shaped to connect the first suspension arm 246 at an angle with respect to the front of the frame 214. One having ordinary skill in the art will appreciate that a number of different front plate shapes can be employed to establish this angled connection. By way of example only, the suspension front plate 250 can have a wing, flange, arm, tab, or other portion 253 that provides a mounting location disposed at an angle with respect to the front of the frame 214. In embodiments in which both front independent suspension systems are connected to a common suspension front plate 250 (see FIGS. 21-26), the suspension front plate 250 can have two such portions 253 providing two mounting locations disposed at respective angles with respect to the front of the frame 214. For different suspension and handling characteristics of the lawn mower 200, the first suspension arm 246 in some embodiments can be connected to the suspension front plate 250 in one of two or more provided locations. By way of example only, the bolt 264 in the illustrated embodiment can be passed through one of a series of apertures in the suspension front plate 250 (e.g., arranged in a horizontal, vertical, or diagonal line, in a curved line, and the like). Connection to each different aperture can thereby provide a different resting position of the front independent suspension assembly 216 to provide different handling characteristics of the lawn mower 200.

With continued reference to FIGS. 22 and 23, the second suspension arm 248 in the illustrated embodiment is mounted to the front frame 214 by a side pivot assembly 270. The side pivot assembly 270 in the illustrated embodiment has the same or similar elements as the front pivot assembly 252. The second suspension arm 248 can be connected to the front frame 214 via a suspension side plate 251. In some embodiments, the second suspension arm 248 is connected to a wing, flange, extension, tab, or other portion 272 of the suspension side plate 251 disposed at an angle with respect to the side of the front frame 214 for the same reasons discussed above. A bolt 264 can be received within a ball joint 260, joint seals 262, a spacer 276, and an aperture 274 in the suspension side plate 251, and can be retained therein by a nut 268.

The alternative assemblies and elements described above with reference to the connection between the first suspension arm 246 and the suspension front plate 250 (or directly to the front frame 214 in other embodiments) apply equally to the connection between the second suspension arm 248 and the suspension side plate 251 or front frame 214.

The front and side pivot assemblies 252 and 270 allow the suspension arms 246, 248 to move in a substantially upward and downward vertical direction relative to the front frame 214. Depending at least partially upon the lengths of the first and second suspension arms 246, 248 and the location of their direct or indirect connection to the front frame 214, other movement such as curved or horizontal movement is possible.

In some embodiments of the present invention, it is desirable to strengthen the front independent suspension assemblies 216 and/or to provide additional structure to which other elements, structure, and devices of the front independent suspension assemblies 216 can be connected. Such additional structure can include one or more plates, rods, bars, tabs, wings, extensions, bosses, platforms, struts, and other framework connected to the first suspension arm 246, the second suspension arm 248, and/or the joint 236. These elements and structure can be connected to the suspension arms 246, 248 and joint 236 in any conventional manner, including those manners described above with reference to the connection between the first and second suspension arms 246, 248 and the joint 236. In the illustrated embodiment for example, a support plate 278 is positioned between the first suspension arm 246 and the second suspension arm 248 (either below the arms 246, 248 as illustrated in FIGS. 21-26, above the arms 246, 248, or on substantially the same level as the arms 246, 248) and can be welded to both arms 246, 248.

Some embodiments of each front independent suspension assembly 216 according to the present invention have a shock absorber 302 and/or a suspension spring 288. The shock absorber 302 and the suspension spring 288 can be connected between the front frame 214 and the front independent suspension assembly 216 to absorb shock transmitted from the wheels 222 and to bias the front independent suspension assembly 216 in a downward direction.

The shock absorber 302 can be a conventional hydraulic shock absorber. However, the shock absorber 302 can take a number of other forms, including without limitation an air shock, an airbag, a coil, torsion, or other spring, and the like. Although the shock absorber 302 can be connected in any conventional manner to the front frame 214 and to any part of the front independent suspension assembly 216, the shock absorber 302 in the embodiment illustrated in FIGS. 21-26 is located between and connected to the support plate 278 and the front frame 214 (or a fixture on the front frame 214). In this regard, the shock absorber 302 can be welded or brazed to the support plate 278 and front frame 214, can be connected thereto with bolts, screws, rivets, pins, clips, clamps, or other conventional fasteners, or can be connected thereto in any other manner desired. In some embodiments, the shock absorber 302 can be received through an aperture 280 in the support plate 278 for connection to a bottom or underside portion thereof.

In the embodiment illustrated in FIGS. 21-26, the shock absorber 302 has a top mount 304 and a bottom mount 306, each mount 304 and 306 having an aperture 308 and 310, respectively, to receive fasteners 312 and 324 therethrough. The fasteners 312, 324 (which can be bolts as shown in the figures or can be any other conventional fastener desired) can be received through one or more apertures 286, 322 in the support plate 278 and a bracket 320 extending from the front frame 214 and through the apertures 308, 310 in the top and bottom mounts 304, 306 of the shock absorber 302. In some embodiments such as that shown in the figures, the support plate 278 can be shaped to define a bracket 282 for connection to the bottom mount 306 of the shock absorber 302. Nuts 318, 332 or other fasteners can be employed to secure the fasteners 312, 324 once installed. Additional hardware such as spacers 314, 316, 328, 330 and washers 326 can be employed as needed to connect the shock absorber 302 to the front frame 214 and to the rest of the front independent suspension assembly 216.

The suspension spring 288 in the embodiment of FIGS. 21-26 is a coil spring that can be retained in position in a number of manners in order to bias the rest of the front independent suspension assembly 216 in a downward direction. In some embodiments for example, the suspension spring 288 is received upon a spring retainer 284 on the support plate 278 and upon a spring retainer 290 connected to the front frame 214. The spring retainers 284, 290 can be clips, clamps, or other elements employed to hold the spring 288 in place. In the embodiment illustrated in FIGS. 21-26, the spring retainers 284, 290 are inserts that are received within the ends of each spring 288 and are connected to the support plate 278 and the front frame 214 in any conventional manner. In other embodiments, the spring retainers 284, 290 can be sockets within which the ends of the springs 288 are received, recesses in the support plate 278 and front frame 214 (or structure attached thereto), clamps, brazing, or welds holding either or both ends of the spring 288 in place, and the like. Any other manner of holding the springs 288 in place can instead be employed as desired.

As an alternative to connection of a spring retainers 284, 290 directly to the support plate 278 and front frame 214, either or both of these retainers 284, 290 can be connected to an adjusting element or device for changing the amount of compression of the spring 288. For example, the upper end of the springs 288 in the illustrated embodiments each seat against an adjusting plate 292 received within a spring seat 294 defined by the front frame 214 or connected to the front frame 214 in any conventional manner. The spring seat 294 can be provided with an aperture 296 within which is received an adjustment screw 298 or other threaded fastener. The screw 298 can be received through the spring seat aperture 296 and into an aperture in the adjusting plate 292 so that turning the screw 298 causes the adjusting plate 292 to compress or reduce the compression upon the spring 288. If desired, one or more guides 299 can extend from the adjusting plate 292 to be received within extensions of the spring seat aperture 296 or dedicated apertures in order to prevent the adjusting plate 292 from turning with the screw 298. Once the screw 298 has been turned to move the adjusting plate 292 to a desired position, a nut 300 can be tightened on the screw 298 to hold the screw 298 and adjusting plate 292 in place.

Although the spring seat 294, adjusting plate 292, adjustment screw 298, and nut 300 are described above as being associated with an upper end of the spring 288, this type of adjustment mechanism can also or instead be provided on the bottom end of the spring 288. In addition, it should be noted that a number of other spring adjustment mechanisms exist and can be used to adjust compression of the springs 288 in the present invention. Each of these alternative spring adjustment mechanisms falls within the spirit and scope of the present invention.

As the front independent suspension assemblies 216 of the lawn mower 200 travel in generally upward and downward vertical directions due to the front and side pivot assemblies 252 and 270 traversing uneven terrain, the shock absorbers 302 (if used) dampen the shock delivered to the mower front frame 214, chassis 212, and operator. This creates a more comfortable ride for the operator, thereby allowing the operator to run the mower 200 at more efficient speeds. The front independent suspension assemblies 216 can also absorb a significant amount of vertical movement caused by the uneven terrain, thereby preventing much of the vertical movement of the front frame 214 and chassis 212. As a result, vertical movement of the cutter deck 208 can be reduced to improve the cutting performance of the lawn mower 200. In addition, when one of the front wheels 222 runs over a large rock, bump, dip, hole, or otherwise experiences a change in elevation causing the wheel 222 to move vertically upward or downward, the improved front independent suspension assembly 216 of the present invention dampen the effect on the other wheels. Thus, the wheels maintain better contact with the ground, giving the lawn mower 200 better traction.

In many respects, the front suspension systems 416, 516 employed in the exemplary embodiments of the present invention illustrated in FIGS. 27-30 and 31-34 are similar in construction and operation to those described above with reference to the embodiment illustrated in FIGS. 21-26. Accordingly, with the exceptions described below and those discussed earlier, reference is hereby made to the description of the embodiment illustrated in FIGS. 21-26 for details regarding the suspension systems 416, 516 illustrated in FIGS. 27-30 and 31-34.

In the embodiment of the present invention illustrated in FIGS. 27-30, the shock absorber 402 of each front suspension system 416 is located within the spring 488 of the same system 416. This shock absorber and spring assembly 454 is connected to the front suspension arm 446, and can be secured thereto with flanges, bosses, plates, or other structure as desired. In addition, this shock absorber and spring assembly 454 is connected to the frame 414 via a bracket 456 extending from the frame 414, and is connected to the first suspension arm 446 via a bracket 455. Although the connection locations of the shock absorber and spring assembly 454 can be located to position the shock absorber and spring assembly 454 in a substantially vertical orientation, in some embodiments (such as that shown in FIGS. 27-30), the shock absorber and spring assembly 454 is instead oriented at acute angle toward the frame 414.

In the embodiment illustrated in FIGS. 31-34, the shock absorber 502 of each front independent suspension system 516 is located within the spring 588 of the same system 516. The shock absorber and spring assembly 554 is connected to the second suspension arm 548, and can be secured thereto with flanges, bosses, plates, or other structure as desired. In addition, this shock absorber and spring assembly 554 is connected to a pivotable mount 560, such as by using similar hardware and methods of attachment as the shock absorber 302 of FIGS. 21-26 or in any other suitable manner.

The pivotable mount 560 can take a number of different forms, each having a point about which the pivotable mount 560 pivots responsive to force exerted by the shock and spring assemblies 554 in upward and downward movement of the front independent suspension systems 516. By way of example only, the pivotable mount 560 can be a beam, bar, rod, tube, plate, plate structure (see FIGS. 31-34), frame, or other element capable of pivoting about a pivot point and to which the front independent suspension systems 516 are connected. In some embodiments such as that shown in FIGS. 31-34, the pivotable mount 560 is pivotable about an axis near or at a central longitudinal axis of the mower 500 (although other pivot locations are possible). Also, in some embodiments of the present invention such as that shown in FIGS. 31-34, the shock absorber and spring assemblies 554 are connected at opposite ends of the pivotable mount 560 (although the shock absorber and spring assemblies 554 need not necessarily be connected at ends of the pivotable mount 560 to function as desired).

In some embodiments, the pivotable mount 560 is pivotably coupled to the frame 514 via conventional fasteners, and is responsive to upward and downward movement of both front wheels 522. One or more spacers and other fastening elements can be employed to pivotably connect the pivotable mount 560 to the frame 514.

By connecting the front suspension systems 516 to the frame 514 via a pivotable mount 560 as just described, the motion of each front suspension system 516 can be at least partially dependent upon the motion of the other front suspension system 516 (e.g., upward movement of one front wheel 522 generating downward force upon the other front wheel 522). In some embodiments, the shock absorber and spring assemblies 554 are replaced by one or more bars, tubes, beams, or other structure absorbing little or no motion of either front wheel 522, thereby transmitting motion of one front wheel 522 to the other front wheel 522. However, a higher degree of independent movement of the front wheels 522 is enabled by connecting the front wheel suspension systems 516 to the pivotable mount 560 via shock absorbers 502 and/or springs 588, both of which can dampen the transmission of one wheel's motion to the pivotable mount 560 and to the other front wheel 522.

In some embodiments, the connection of the front independent suspension systems 516 to a pivotable mount 560 as described above provides improved traction for the rear wheels 506 of the mower 500.

One having ordinary skill in the art will also recognize that a number of the elements and structure in the embodiments described can be replaced by other elements and structure performing the same functions and still falling within the spirit and scope of the present invention. For example, while a number of lawn mower embodiments used in connection with the present invention have the cutter deck positioned between the front and rear wheels, the present invention is also applicable to mowers having a cutter deck cantilevered from the chassis so that it is located forward or rearward of the front or rear wheels, respectively. Also, the springs 288, 488, 588 described above and illustrated in the figures are helical compression springs. One having ordinary skill in the art will appreciate that other types of springs can instead be employed with the front independent suspension assemblies 216, 416, 516 of the present invention, such as torsion bars and other torsion springs, leaf springs, and the like. Each of these alternative springs can be positioned between the frame 214, 414, 514 and the front independent suspension assemblies 216, 416, 516 in order to provide the desired downward force upon the front wheels 222, 422, 522.

Furthermore, the various embodiments of the present invention shown in FIGS. 21-34 can include alternate elements and alternate structure that are different in appearance and/or form than those illustrated, but that still perform the same or similar functions. Such alternate elements and structure fall within the spirit and scope of the present invention.

The present invention is also applicable to lawn mowers having more or fewer than four wheels and to lawn mowers designed for the operator to walk or ride behind or in front of the mower. By way of example only, the present invention finds applicability to walk-behind mowers, push mowers, and mowers with seats cantilevered forward or rearward of the front or rear wheels, respectively.

Accordingly, the embodiments described above and illustrated in the figures are presented by way of example only and not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims. 

1. A mower, comprising: a frame including a front, opposite sides, at least one front beam located at the front of the frame with respect to a forward direction of movement of the mower, and at least one side beam located along each of the opposite sides of the frame; first and second front wheels; each of the first and second front wheels coupled to the at least one front beam at the front of the frame and coupled to a respective one of the side beams at a side location of the frame disposed a distance from the front of the frame, the first and second front wheels independently movable upward and downward with respect to one another and coupled to the frame for upward and downward movement with respect to the frame; a cutter deck; and at least one cutter in the cutter deck, the cutter and cutter deck coupled to the first and second front wheels for upward and downward movement responsive to upward and downward movement of the first and second front wheels.
 2. The mower as claimed in claim 1, further comprising a pair of first suspension arms, each first suspension arm coupled to a respective one of the front wheels and coupled to the front of the frame.
 3. The mower as claimed in claim 2, further comprising a pair of second suspension arms, each second suspension arm coupled to a respective one of the front wheels and coupled to a respective one of the side locations on the frame.
 4. The mower as claimed in claim 1, further comprising a pair of suspension arms, each suspension arm coupled to a respective one of the front wheels and coupled to a respective one of the side locations on the frame.
 5. The mower as claimed in claim 4, wherein the cutter deck is coupled to at least one of the suspension arms for upward and downward movement therewith responsive to upward and downward movement of at least one of the first and second wheels.
 6. The mower as claimed in claim 2, wherein the pair of first suspension arms are connected to the front of the frame a distance apart from one another.
 7. The mower as claimed in claim 3, wherein the first and second suspension arms define an acute angle therebetween.
 8. The mower as claimed in claim 2, further comprising a joint coupled to each front wheel; wherein each first suspension arm is coupled to a respective one of the joints; and each front wheel is coupled to the front of the frame via one of the joints and one of the first suspension arms.
 9. The mower as claimed in claim 4, further comprising a joint coupled to each front wheel; wherein each suspension arm is coupled to a respective one of the joints; and each front wheel is coupled to a respective one of the side locations on the frame via one of the joints and one of the suspension arms.
 10. The mower as claimed in claim 3, further comprising a joint coupled to each front wheel; wherein each first suspension arm is coupled to a respective one of the joints; each second suspension arm is coupled to a respective one of the joints; and each front wheel is coupled to the front of the frame via one of the joints, one of the first suspension arms, and one of the second suspension arms.
 11. The mower as claimed in claim 3, wherein the first and second suspension arms are pivotably coupled to the frame.
 12. The mower as claimed in claim 1, further comprising a first spring positioned to bias the first wheel in a downward direction and a second spring positioned to bias the second wheel in a downward direction.
 13. The mower as claimed in claim 12, wherein the first and second springs are adjustable.
 14. The mower as claimed in claim 1, further comprising a first shock absorber positioned to absorb shock transmitted from the first wheel and a second shock absorber positioned to absorb shock transmitted from the second wheel.
 15. The mower as claimed in claim 2, wherein each of the pair of first suspension arms are oriented and connected at an acute angle with respect to the front beam.
 16. The mower as claimed in claim 3, wherein the second suspension arms are oriented and connected at an angle with respect to the side beams.
 17. The mower as claimed in claim 4, wherein the suspension arms are oriented and connected at an angle with respect to the side beams. 18-38. (canceled)
 39. A method of moving a front wheel with respect to a frame of a mower, the method comprising: providing first and second suspension arms coupled to the front wheel; pivoting the first suspension arm about a connection point on a front of the frame; pivoting a second suspension arm about a connection point on a side of the frame; and moving the front wheel vertically with respect to the frame; moving a cutter deck of the mower vertically with respect to the frame responsive to moving the front wheel vertically with respect to the frame.
 40. The method as claimed in claim 39, further comprising pivoting the front wheel with respect to the first and second suspension arms and with respect to the frame.
 41. The method as claimed in claim 39, wherein pivoting the first suspension arm about a connection point includes pivoting the first suspension arm about an axis that is non-orthogonal with respect to the frame at the connection point of the first suspension arm.
 42. The method as claimed in claim 39, wherein pivoting the second suspension arm about a connection point includes pivoting the second suspension arm about an axis that is non-orthogonal with respect to the frame at the connection point of the second suspension arm.
 43. The method as claimed in claim 39, further comprising biasing the wheel and the first and second suspension arms in a downward direction.
 44. A mower, comprising: a frame including a front; and opposite sides; a cutter deck; at least one cutter in the cutter deck; first and second front wheels, each of the first and second front wheels coupled to the frame by a suspension arm; and a beam pivotably coupled to the frame and coupled to the suspension arms, the beam being pivotable responsive to upward and downward movement of the first and second front wheels.
 45. The mower as claimed in claim 44, wherein the beam is coupled to the frame at the front of the frame.
 46. The mower as claimed in claim 44, wherein each of the first and second front wheels is coupled to the front of the frame and is coupled to a respective one of the side beams of the frame at a side location of the frame disposed a distance from the front of the frame, the first and second front wheels movable upward and downward with respect to one another and coupled to the frame for upward and downward movement with respect to the frame.
 47. The mower as claimed in claim 44, wherein: the suspension arm is a first suspension arm, each of the first and second front wheels also coupled to the frame by a second suspension arm, the first suspension arm of each front wheel being coupled to the front of the frame, and the second suspension arm of each front wheel being coupled to a side of the frame; and the front wheels and the first and second suspension arms of each front wheel are movable upward and downward relative to the frame responsive to changes in elevation of ground traversed by the front wheels.
 48. The mower as claimed in claim 47, further comprising a shock absorber positioned to absorb shock received from the first front wheel, the shock absorber coupled between the beam and at least one of the first and second suspension arms of the first front wheel.
 49. The mower as claimed in claim 48, wherein the shock absorber is coupled between the beam and the second suspension arm.
 50. The mower as claimed in claim 44, wherein the beam includes: a first end; a second end; and a middle portion between the first and second ends and pivotably coupled to the front of the frame.
 51. The mower as claimed in claim 50, wherein the first end is coupled to the first suspension arm and the second end is coupled to the second suspension arm.
 52. A mower, comprising: a frame including a front, opposite sides, at least one front beam located at the front of the frame with respect to a forward direction of movement of the mower, and at least one side beam; first and second front wheels; a cutter deck coupled to the first and second front wheels, the cutter deck movable upward and downward responsive to upward and downward movement of the first and second front wheels with respect to the frame; and at least one cutter in the cutter deck.
 53. The mower as claimed in claim 52, wherein each of the first and second front wheels is coupled to the frame for movement independent of the other front wheel.
 54. The mower as claimed in claim 52, wherein the cutter deck is responsive to movement of the first front wheel substantially independent of movement of the second front wheel.
 55. The mower as claimed in claim 54, wherein upward and downward movement of the first and second front wheels causes upward and downward movement of the cutter deck.
 56. The mower as claimed in claim 54, wherein: the first and second front wheels are each coupled to the frame via respective first and second arms; and the cutter deck is coupled to at least one of the first and second arms of each of the first and second front wheels.
 57. A method of coupling movement of a first front wheel and a second front wheel of a mower, the method comprising: pivotably coupling a beam to a frame of the mower, the beam pivotable about a longitudinal axis of the mower and extending between sides of the frame of the mower; pivotably coupling a first arm to a first side of the frame; pivotably coupling a second arm to a second side of the frame; coupling the first arm to a first end of the beam; coupling the second arm to a second end of the beam; coupling the first front wheel to the first arm to control movement of the first front wheel, movement of the first front wheel generating pivoting movement of the beam with respect to the frame; and coupling the second front wheel to the second arm to control movement of the second front wheel, movement of the second front wheel generating pivoting movement of the beam with respect to the frame.
 58. (canceled)
 59. A mower, comprising: a chassis having a front portion and a rear portion; a prime mover mounted on the chassis; a cutter deck supported by the chassis; front wheels attached to the front portion of the chassis; two drive wheel assemblies on different sides of the rear portion of the chassis, each drive wheel assembly connected to the chassis by at least one link pivotable with respect to the chassis; at least one biasing member associated with the drive wheel assemblies and positioned to bias the drive wheel assemblies in a downward direction; wherein the drive wheels and front wheels support the chassis for movement over a surface; each drive wheel assembly comprising a drive wheel powered for rotation by the prime mover; and wherein each drive wheel assembly moves up and down relative to the chassis, respectively against and with force exerted by the at least one biasing member, independently of movement of the other drive wheel assembly.
 60. The mower as claimed in claim 59, wherein the cutter deck is suspended from the chassis between the front portion and rear portion of the chassis, and wherein the cutter deck hangs at a predetermined distance from the chassis, the cutter deck being movable upwardly under influence of an upward force.
 61. The mower as claimed in claim 59, wherein each drive wheel assembly comprises a motor independently powered by the prime mover.
 62. The mower as claimed in claim 59, wherein the biasing member comprises a non-metal material.
 63. The mower as claimed in claim 59, wherein the biasing member is a spring.
 64. A mower, comprising: a chassis having a front portion and a rear portion; a prime mover mounted on the chassis; a cutter deck supported by the chassis; front wheels attached to the front portion of the chassis; two drive wheel assemblies on different sides of the rear portion of the chassis, each drive wheel assembly connected to the chassis by at least one link assembly; each link assembly pivotably connected at an inner end to a pivot point on the chassis and pivotably connected at an outer end to a pivot point on the wheel assembly; at least one biasing member coupled to each drive wheel assembly; wherein the drive wheels and front wheels support the chassis for movement over a surface; each drive wheel assembly comprising a drive wheel rotated by the prime mover; and wherein each drive wheel assembly moves relative to the chassis, respectively against and with force exerted by the biasing member, independently of movement of the opposing drive wheel assembly.
 65. The mower as claimed in claim 65, wherein the biasing member comprises a non-metal material.
 66. The mower as claimed in claim 65, wherein the biasing member is a spring.
 67. A mower comprising; a chassis having a front portion, a rear portion, and a longitudinal axis; a subframe pivotably connected to the front portion of the chassis for pivoting about the longitudinal axis and adapted to receive two front wheels; a prime mover mounted on the chassis; the two front wheels attached to different sides of the subframe; two drive wheel assemblies, one each on different sides of the rear end of the chassis and connected thereto by at least one link assembly, each link assembly comprising at least one link pivotably connected at an inner end to a pivot point on the chassis and pivotably connected at an outer end to a pivot point on the wheel assembly, each drive wheel assembly comprising a wheel driven by the prime mover; a biasing member pressing on each wheel assembly for urging the wheel assembly downwardly; and wherein each drive wheel assembly moves up and down relative to the chassis, respectively against and with force exerted by the biasing member, independently of movement of the opposing wheel assembly.
 68. The mower as claimed in claim 67, further comprising a cutter deck suspended beneath the chassis between the front and rear wheels by a deck hanger, the deck hanger holding the cutter deck beneath the chassis and limiting the downward movement of the deck to a predetermined distance while enabling the deck to move upwardly under the influence of an upward force.
 69. The mower as claimed in claim 67, wherein each drive wheel assembly comprises a motor independently powered by the prime mover.
 70. The mower as claimed in claim 67, wherein the biasing member comprises a non-metal material.
 71. The mower as claimed in claim 67, wherein the biasing member is a spring.
 72. The mower as claimed in claim 67, wherein each drive wheel assembly further comprises a motor powered by the prime mover, and wherein variation of relative speed of the drive wheels of the two wheel assemblies alters the direction of travel of the mower.
 73. A mower, comprising: a chassis; a prime mover mounted on the chassis; a cutter deck supported from the chassis; two pairs of wheels, one each attached to the chassis at different ends thereof; wherein: the wheels support the chassis for movement over a surface, one of the pairs of wheels comprises drive wheels rotated by the prime mover; and each of the one pair of drive wheels is attached to the chassis by at least one link assembly pivotably connected to the chassis and the drive wheel; and each drive wheel moves up and down relative to the chassis, respectively against and with force transmitted to the wheel by a biasing member, independently of movement of the other wheel of the pair.
 74. The mower as claimed in claim 73, wherein each drive wheel is independently rotated by the prime mover, and wherein change in relative rotational speed of the drive wheels alters the direction of travel of the mower.
 75. The mower as claimed in claim 73, wherein the at least one link assembly causes each drive wheel to move vertically up and down without change in camber.
 76. The mower of as claimed in claim 73, wherein the cutter deck is suspended from the chassis, whereby the cutter deck is movable in an upward direction relative to the chassis when an upward force is applied to the deck portion; the mower further comprising a lifting bracket coupled to the cutter deck for lifting the deck portion upwardly when a drive wheel moves upwardly. 